1. Field of the Invention
This invention relates to a liquid treating device for chemical analysis apparatus which is provided with a nozzle for successively sucking various kinds of liquids such as a test liquid, wash liquid, reagent, standard liquid having a known ion concentration or the like and which can effectively prevent contamination between successive liquids to be treated.
2. Description of the Prior Art
Various chemical analysis apparatus which are provided with a nozzle for sucking a number of test liquids in succession and in which these test liquids are fed to a flow cell or discharged into a reaction pipe so as to effect a desired measurement have heretofore been proposed.
In such analysis apparatus, it is necessary to effectively prevent contamination between successive test liquids in order to accurately effect the desired measurement on the successive test liquids. To this end, a liquid treating device which is operative to move the nozzle to a washing position other than a test liquid sucking position or test liquid discharging position after a given treatment has been completed for one test liquid and spray a wash liquid against the outer wall of the nozzle and discharge the wash liquid from the nozzle so as to wash the inner and outer walls of the nozzle has been proposed. Another liquid treating device which makes use of a dilute liquid as the wash liquid in the case of discharging the test liquid from the nozzle into the reaction pipe and which is operative to discharge the test liquid together with the dilute liquid into the reaction pipe so as to wash the inner wall of the nozzle and clean the outer wall of the nozzle by another means such as wiping treatment or the like.
But, the former liquid treating device has the disadvantage that since provision must be made of a separate washing position and the nozzle is required to be moved to this position, the device is complex in construction and troublesome in operation. Whereas, the latter liquid treating device has the disadvantage that since it is impossible to sufficiently wash the inner wall of the nozzle by the dilute liquid having a given dilution ratio and the outer wall of the nozzle must be cleaned by another means, the device is also complex in construction and troublesome in operation.
A so-called flow-through type ion concentration measuring apparatus comprising a flow cell provided with a comparative electrode and an ion sensor selectively sensitive to a specified ion and operative to suck a test liquid through a nozzle into the flow cell so as to measure a specified ion concentration of the test liquid has heretofore been proposed. In such ion concentration measuring apparatus, in order to accurately measure the ion concentration of the successive test liquids, it is required to effectively prevent contamination between successive test liquids in the nozzle, flow cell and liquid transfer pipe interposed between these nozzle and flow cell and to always effect measurement on the basis of a correct calibration line. In order to satisfy these two requirements, another liquid treating device has been proposed in which a nozzle is moved to a washing position after the ion concentration of one test liquid has been measured and a wash liquid is sprayed against the outer wall of the nozzle and the wash liquid is sprayed out of the nozzle through the flow cell and liquid transfer pipe in a direction opposed to the sucking direction of the test liquid, thereby washing the inner and outer walls of the nozzle, liquid transfer pipe and flow cell.
In the above mentioned ion concentration measuring apparatus, use is made to two kinds of standard liquids having different known ion concentrations and such ion concentrations are measured at two calibration points and a line drawn through these two points defines a calibration line. The calibration line may be defined at a suitable time, for example, prior to measurement of a plurality of successive test liquids. But, in order to effect an accurate measurement on each test liquid, it is preferable that two kinds of standard liquids are measured in the course of measuring the successive test liquids to correct the calibration line and that prior to the measurement of each test liquid, the measurement on either one of the standard liquids is effected to correct the calibration line.
But, the use of the measures described above for prevention of contamination, correction of calibration line or the like provides the disadvantage that the device is complex in construction and troublesome in operation.
Meanwhile, in almost all of the conventional flow-through type ion concentration measuring apparatus, when the apparatus is ready for measurement, the flow cell becomes vacant. If the flow cell is vacant, the comparative electrode and the electrode portions of the ion sensor become dried and are deteriorated in their characteristics, and as a result, the apparatus can not effect accurate measurement and provides a material decrease in durability.